OK...A new question on stringers

Discussion in 'Fiberglass and Composite Boat Building' started by dem45133, Aug 2, 2006.

  1. dem45133
    Joined: Aug 2006
    Posts: 38
    Likes: 2, Points: 0, Legacy Rep: 22
    Location: ohio

    dem45133 Junior Member

    Ive been reading a bunch of these on this and noticed something that appears to be common for all the glass boats.

    For you old timers and hopfully a marine architect/designer, I have a question. If all the wood will eventually rot and yet it is critical to structual support... why then is it always (apparently) basically total encapsulated (but never 100%, nor will it ever stay that way) in glass. Wouldn't it be better to have the stringers only glass strapped in place with a suitable open span between and the straps suitably heavy. This would keep the wood (and not plywood for long spanning stringer) open and totally dryable. Seems its the trapped water creating the problem.

    The boat repair I am considering is a glass 27 ft full inboard, but my old 1962 plywood runabout I have since 1970 still has good wood in its structures (oak)...but they are all open and exposed and never stay wet for all that long.

    Seems all the glass boats are badly designed (as far as rot potential is concerned). There has to be reasons... why would anyone design them to be gone in ten years? I truely hope they have not totally bought into the planned obsolecence that blatenly. May be. But if one would have to repair it... it makes no sense to me to duplicate their arrogance.

    How would one go about using open beams (say of oak, or catalpa (rot and bug resistant), or mohogany, or ?? and "strap" glass them in... Same on the transom. Seams to me the inside should be exposed wood and allow the wood to ventilate and dry. Seems to me also on the transom that air channels should be incorporated between the bonded glass and the transom wood at periodicc intervals tied directly to flowable venting while under way and the powered evacuation fans when not.

    When I first thought about this boat an heard it need a stringer... being an relatively creative and accomplished woodworker I thought it couldn't be that bad a project. Not so sure now.... Yea I can do it, but it will not ever be a permanent repair... its not a permanent design to start with.

    But its seems every glass boat is designed the same. The engineer in me just can't believe what I'm seeing. What am I missing?

    Humm.. shrink-swell for one... but ok, say its dry when built, and the glass is esencially swell proof as far as water is concerned (not temperature)... but it WILL eveually get saturated and stress the H out of the glass everywhere its is total encapsulated especially if locked end to end on long continuos pieces... like a stringer. A good portion of your glass's design strength is now consummed by internal pressure from the wood. As a matter of fact, those forces can get extreme and over come the glass I would suspect, especially if it there overwinter and freezes. Now you have ice expansion as well.

    I know, you can't let me think about anything... I'll find issues. But I am very curious... and if there is a way to improve on the design (that was planned obselecence or mass production oriented), I'd like to know.

    Any comments? I can't have been the only one to notice this.

    Dave
    Hillsboro, Ohio
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.